.leftfix {
    position: fixed;
    top: 0;
    left: 0;
    width: 280px;
    height: 100%;
    background-color: white;
    z-index: 3;
}

.leftbtn {
    position: fixed;
    left: 20px;
    bottom: 20px;
    width: 60px;
    height: 60px;
    line-height: 60px;
    font-size: 40px;
    text-align: center;
    background-color: #6bbef5;
    color: white;
    border-radius: 50%;
    cursor: pointer;
    z-index: 3;
}

.leftclose {
    position: absolute;
    top: 0;
    right: 0;
    padding: 10px 10px 0 0;
    cursor: pointer;
}

.leftcont {
    height: 100%;
    overflow: hidden auto;
}

.leftitem {
    position: relative;
    left: -30px;
    padding: 20px 20px 0;
    opacity: 0;
    word-break: break-all;
    cursor: pointer;
    animation: ani 1000ms forwards;
}

.cont {
    margin-left: 280px;
}

@keyframes ani {
    0% {
        opacity: 0;
        left: -30px
    }

    100% {
        opacity: 1;
        left: 0;
    }
}